This invention relates in general to panels useful in making strengthened wood-frame construction so that the construction has increased resistance to high wind, earthquake and blast loadings.
A very common wood frame construction method uses wood or steel studs or wood or steel framing with plywood or Oriented Strand Board (OSB) sheathing panels or stucco sheathing. The framing/sheathing combination forms shear walls and horizontal diaphragms which resist horizontal and vertical loads applied to the structure. This form of construction is used in the majority of single family homes in the United States, as well as a significant portion of multi-family, commercial and industrial facilities.
While the system has generally performed well, the economic losses in the United States due to natural disasters, such as hurricanes, earthquakes and tornadoes, have been mounting. The economic losses caused by these natural disasters in the United States has averaged about $1 billion/week in recent years. Most of these losses are due to hurricanes (80%) and earthquakes (10%). For example, the loss of roof sheathing under hurricane winds has often been attributed to improper fastening of the sheathing to the framing, such as by the use of larger nail spacing than allowed by code, nails missing the support framing members, or over-driven nails. Inadequate panel-to-framing nailing schedules do not allow the full shear strength of the panel to be developed, resulting in premature failures of shear walls, possibly leading to severe damage or collapse of the structure. Loss of sheathing in hurricanes weakens the roof structure and can lead to roof failures. The water damage resulting from a loss of roof sheathing or roof failures has been a major contributor to economic losses in hurricanes. Surveys also show that a significant portion of the damage resulting from hurricanes or earthquakes occurs in nonstructural parts of the home due to excessive deformation or movements of the structure. The cost to repair nonstructural damage often makes it necessary to rebuild the structure rather than to repair it.
While the knowledge to mitigate hurricane and earthquake damage exists today, building code provisions are often misunderstood by builders, and compliance with regulations is difficult to enforce because of the difficulty of inspecting in the field. As a result, surveys show that a significant portion of the damage to homes and property caused by natural disasters is due to lack of conformance to codes. Improper connections between walls at building corners, such as non-overlapping top plates or improper or missing hold-downs to tie the shear walls to the foundations, are further examples of poor construction practices that are difficult to inspect.
Therefore, there is a need for easy-to-manufacture, inexpensive construction panels suitable for providing a strengthened and stiffened construction for improved resistance to high wind loadings, and increased ductility and energy dissipation capacity to reduce earthquake damage. The construction panels should increase the strength and ductility of wood buildings and reduce the deformation of the buildings to limit damage to non-structural members.
The above objects as well as other objects not specifically enumerated are achieved by a wood sheathing panel, suitable for use in building construction, that includes reinforcement strips of fiber reinforced polymer material incorporated into the panel. The reinforcement strips cover an area that is within the range of from about 5 to about 50 percent of the surface area of the panel.
In a specific embodiment of the invention, the reinforcement strips of fiber reinforced plastic material are incorporated in the perimeter of the panel. In another specific embodiment of the invention, the reinforcement strips of fiber reinforced plastic material are incorporated into the corners of the panel.
In another specific embodiment of the invention, the spacing of the intermittently incorporated reinforcement strips generally coincides with a standard spacing of framing members so that when the wood sheathing panel is applied to a building frame, the reinforcement strips are generally aligned with framing members of the building.
According to this invention, there is also provided a plurality of wood sheathing panels assembled together in building construction as one element of a group consisting essentially of shear walls, horizontal diaphragms and roof diaphragms, where the wood sheathing panels are suitable for use in building construction, and include reinforcement strips of fiber reinforced polymer material incorporated into the panel. The reinforcement strips cover an area that is within the range of from about 5 to about 50 percent of the surface area of the panel.